Radio transmitting/receiving apparatus and method, terminal apparatus, base station apparatus and wireless communication system

ABSTRACT

A terminal apparatus ( 1 ) which is a radio transmitting/receiving apparatus receives, from a femto cell base station (home eNB), a pilot channel signal for reception quality measurement and a synchronization channel signal for synchronization. The terminal apparatus ( 1 ) has a whitelist stored therein indicative of an accessible femto cell, and determines whether or not a CSG cell of handover destination is accessible based on a PCI of the CSG cell acquired from the synchronization channel and the whitelist. The terminal apparatus ( 1 ) then adds the PCI and a CGI to a measurement report for reception quality, and transmits the measurement report to a macro eNB (base station apparatus ( 2 )). In this way, it is possible to suppress wasteful signaling and prevent unnecessary resources from being reserved even when two or more CSG cells that use the same PCI are present in the macro cell.

BACKGROUND

1. Technical Field

The present invention relates to a radio transmitting/receivingapparatus and method for use in a terminal apparatus and a base stationapparatus that constitute a wireless communication system, andparticularly to a technique for performing a handover from a macro cellto a CSG cell.

2. Description of the Related Art

Conventionally, the Long Term Evolution (LTE) system is known as anetwork system for wireless communication between a base station and aterminal apparatus. The LTE system is a mobile communication system ofnext generation evolved from the Universal Mobile TelecommunicationsSystem (UMTS) and is intended to provide more improved mobilecommunication services.

In the LTE, in addition to a macro cell wireless communication basestation apparatus (Evolved NodeB, or eNB) that is primarily locatedoutdoors and supports a larger cell diameter, it is under considerationto provide a femto cell wireless communication base station apparatus,which supports a cell diameter on the order of tens of meters, in indoorfacilities such as a residence, an office, a restaurant, and a shoppingcenter. Some femto cell wireless communication base station apparatusesunder consideration in the 3rd Generation Partnership Project (3GPP)permit limited groups of members to access the base station apparatuses.Such cells are referred to as a Closed Subscriber Group cell, or CSGcell. A wireless communication base station apparatus that forms a CSGcell is referred to as a Home Evolved NodeB, or HeNB. The macro eNB can,for example, manage two or more different frequency bands (f1, f2, . . ., fn), and the home eNB may be located on a frequency f1.

A wireless communication terminal apparatus (User Equipment, or UE)permitted to have an access is controlled from the network so as toconnect to the home eNB. Specifically, once in the area of the CSG cell,the terminal apparatus is controlled to preferentially connect to thehome eNB even if the terminal apparatus can receive radio signals fromthe eNB. A list of CSG cells that the terminal is permitted to access isreferred to as a whitelist. Each of terminal apparatuses has its ownwhitelist.

Description will now be made to a control method of performing ahandover from a macro eNB to a home eNB in a conventional LTE. (referto, for example, Patent Literature 1 and Non-Patent Literature 1)

An active UE generally receives a measurement control message through aDedicated Control Channel, or DCCH, from the eNB to which the UE isconnected. The measurement control message provides settings for takingreception quality measurements of the current cell and an adjacent cell.The measurement control message includes parameters such as a frequencyand a system to be measured, event information that triggerstransmission of a measurement report to the base station, a signal usedin the measurement, and a duration (gap) for performing the measurement.The UE measures reception quality of the adjacent cell through a pilotchannel (Common Pilot Channel, or CPICH) according to the settings fromthe measurement control message, and transmits the reception qualitymeasurement result in a report (measurement report) to the eNB in aperiodical manner or triggered by a configured event.

It is assumed here that the UE moves to the vicinity of the border ofthe CSG cell. The UE measures the reception quality of the CSG cell,during which the UE acquires a physical cell ID (Physical Cell Identity,or PCI) of the CSG cell by receiving a Synchronization Channel, or SCH.In particular, one PCI is determined among 510 PCIs by a combination ofa signal pattern of a Primary Synchronization Channel (P-SCH) and apattern of a pair of (S1, S2) or (S2, S1) determined from a SecondarySynchronization Channel (S-SCH). The UE then notifies the macro eNB ofthe PCI of the CSG cell subjected to the measurement and the measurementresult.

The macro eNB retains a list of CSG cells contained in the macro cell,and the list of CSG cells include PCIs for each home eNB and a CellGlobal Identity, or CGI. The macro eNB that has received the measurementresult of the CSG cell notified by the UE determines a home eNB that hasthe corresponding PCI from the list of CSG cells contained in the macrocell, and transmits an inquiry (HO request) of whether the UE may beallowed to perform a handover via a Mobility Management Entity(MME)/Gateway (GW) to the home eNB. If the handover of the UE is to bepermitted; the home eNB that has received the HO request reserves inadvance wireless resources appropriate for services provided to the UE,performs acceptance control, and transmits a response (an ACK to the HOrequest) that permits the handover of the UE via the MME/GW to the macroeNB.

Upon receiving the ACK to the HO request from the home eNB, the macroeNB transmits an instruction (HO command) causing a transfer to the CSGcell to the UE, and the UE transmits a random access preamble (RACHpreamble) in order to establish synchronization with the specified homeeNB. Thereafter, when the UE receives a response (random accessresponse, or RACH response) from the home eNB, the UE establishessynchronization with the home eNB and an uplink transmission opportunityis assigned to the UE from the home eNB. Once the synchronization isestablished, the UE transmits a signal (HO confirmation) indicative ofthe completion of handover to the home eNB.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent Laid-Open No. 2007-266732

Non-Patent Literature

-   Non-Patent Literature 1: 3GPP TS36.331 v8.3.0 “Evolved Universal    Terrestrial Radio Access (E-UTRA) Radio Resource Control (RRC)”

In the conventional handover control method, however, UEs deliverreports to eNBs with reference to only PCIs of CSG cells. Therefore, iftwo or more CSG cells that use the same PCI are present in the macrocell for example, the macro eNB may transmit HO requests to more thanone home eNB in response to the measurement report sent from the UE. Insuch a case, there may be wasteful signaling to home eNBs different fromthe home eNB on which the UE actually measured the reception quality.Further, home eNBs, which are different from the home eNB on which theUE actually measured the reception quality, may reserve unnecessaryresources for the UE.

BRIEF SUMMARY Technical Problem

The present invention has been made under such circumstances. It is anobject of the invention to provide a radio transmitting/receivingapparatus capable of suppressing wasteful signaling and preventingunnecessary resources from being reserved even when two or more CSGcells that use the same PCI are present in the macro cell.

Solution to Problem

One aspect of the invention is a radio transmitting/receiving apparatus,and the radio transmitting/receiving apparatus comprises: a receptionunit for receiving, from a macro cell base station, an instruction forhandover to a femto cell contained in a macro cell and receiving, from afemto cell base station, a pilot channel signal for reception qualitymeasurement at the femto cell and a synchronization channel signal forsynchronization; a storage unit for storing a list indicative of anaccessible femto cell among femto cells contained in the macro cell; adetermination unit for determining whether or not a femto cell ofhandover destination is accessible based on a physical cell ID of thefemto cell acquired from the received synchronization channel and thelist; a measurement report creating unit for adding a physical cell IDand a unique cell ID to a measurement report indicative of a result ofmeasurements taken by means of the pilot channel signal, the physicalcell ID being acquired from the synchronization channel and beingindicative of a femto cell from which a signal is being received and theunique cell ID being for uniquely identifying a femto cell contained inthe macro cell and being indicative of the femto cell of handoverdestination determined to be accessible; and a transmission unit fortransmitting the measurement report to the macro cell.

As described below, the present invention has other aspects. Therefore,the disclosure of the invention is intended to provide some of theaspects of the invention, and is not intended to limit the scope of theinvention as described and claimed herein.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a terminalapparatus according to a first embodiment.

FIG. 2 is a diagram for illustrating a cell arrangement according to thefirst embodiment.

FIG. 3 is a block diagram showing a configuration of a base stationapparatus according to the first embodiment.

FIG. 4 is a sequence diagram for illustrating an operation of a wirelesscommunication system according to the first embodiment.

FIG. 5 is a flow chart for illustrating an operation of the terminalapparatus according to the first embodiment.

FIG. 6 is a flow chart for illustrating an operation of the base stationapparatus according to the first embodiment.

FIG. 7 is a block diagram showing a configuration of a terminalapparatus according to a second embodiment.

FIG. 8 is a block diagram showing a configuration of a base stationapparatus according to the second embodiment.

FIG. 9 is a sequence diagram for illustrating an operation of a wirelesscommunication system according to the second embodiment.

FIG. 10 is a sequence diagram for illustrating an operation of thewireless communication system according to the second embodiment.

FIG. 11 is a flow chart for illustrating an operation of the terminalapparatus according to the second embodiment.

FIG. 12 is a block diagram showing a configuration of a terminalapparatus according to a third embodiment.

FIG. 13 is a block diagram showing a configuration of a base stationapparatus according to the third embodiment.

FIG. 14 is a sequence diagram for illustrating an operation of awireless communication system according to the third embodiment.

FIG. 15 is a flow chart for illustrating an operation of the terminalapparatus according to the third embodiment.

FIG. 16 is a block diagram showing a configuration of a terminalapparatus according to a fourth embodiment.

FIG. 17 is a block diagram showing a configuration of a base stationapparatus according to the fourth embodiment.

FIG. 18 is a sequence diagram for illustrating an operation of awireless communication system according to the fourth embodiment.

FIG. 19 is a flow chart for illustrating an operation of the terminalapparatus according to the fourth embodiment.

DETAILED DESCRIPTION

The present invention will now be described in detail. However, thedetailed description below and attached drawings are not intended tolimit the present invention. Rather, the scope of the invention isdefined by the attached claims.

The radio transmitting/receiving apparatus according to the inventioncomprises: a reception unit for receiving, from a macro cell basestation, an instruction for handover to a femto cell contained in amacro cell and receiving, from a femto cell base station, a pilotchannel signal for measurement at the femto cell and a synchronizationchannel signal for synchronization; a storage unit for storing a listindicative of an accessible femto cell among femto cells contained inthe macro cell; a determination unit for determining whether or not afemto cell of handover destination is accessible based on a physicalcell ID of the femto cell acquired from the received synchronizationchannel and the list; a measurement report creating unit for adding aphysical cell ID and a unique cell ID to a measurement report indicativeof a result of measurements taken by means of the pilot channel signal,the physical cell ID being acquired from the synchronization channel andbeing indicative of a femto cell from which a signal is being receivedand the unique cell ID being for uniquely identifying a femto cellcontained in the macro cell and being indicative of the femto cell ofhandover destination determined to be accessible; and a transmissionunit for transmitting the measurement report to the macro cell.

With this configuration, not only the physical cell ID (such as PCI) ofa femto cell (such as a CSG cell) from which a signal is being received,but also a unique cell ID (such as CGI) of the femto cell of handoverdestination is added to the measurement report of the radio quality.Therefore, even when two or more CSG cells that use the same PCI arepresent in the macro cell for example, an accessible CSG cell (a CSGcell of handover destination) can be identified based on the CGI. Inthis way, it is possible to suppress wasteful signaling to home eNBs ofinaccessible CSG cells and prevent unnecessary resources from beingreserved.

The present invention adds not only the physical cell ID of a femto cellfrom which a signal is being received but also a unique cell ID of thefemto cell of handover destination to the measurement report, and canthereby suppress wasteful signaling and prevent unnecessary resourcesfrom being reserved.

A wireless communication system according to embodiments of the presentinvention will now be described below with reference to drawings. Thewireless communication system according to the embodiments includes aterminal apparatus with radio transmitting/receiving functions (such asmobile phones and PDA devices) and a base station apparatus with radiotransmitting/receiving functions. The terminal apparatus and the basestation apparatus are also considered as a radio transmitting/receivingapparatus.

First Embodiment

A wireless communication system according to a first embodiment of thepresent invention will now be described below with reference to FIGS. 1to 6. FIG. 1 is a block diagram showing a configuration of a terminalapparatus 1 according to the embodiment; FIG. 2 is a diagram forillustrating a cell arrangement according to the embodiment; and FIG. 3is a block diagram showing a configuration of a base station apparatus 2according to the embodiment.

First, a cell arrangement according to the embodiment will be describedwith reference to FIG. 2. In an example shown in FIG. 2, a macro eNBmanages macro cells having two different frequency bands (f1, f2), andCSG cells managed by two home eNBs (HeNB 1 and HeNB 2) are both locatedon the macro cell of frequency f1. PCIs of the two CSG cells are both“PCI #2” and both PCIs are the same. In other words, two CSG cells thatuse the same PCI are present in one macro cell in this case. Meanwhile,CGIs of the two CSG cells are “CGI #3” for one CSG cell and “CGI #6” forthe other and the two CGIs are different. Here, the macro eNBcorresponds to a macro cell base station of the invention. The CSG cellcorresponds to a femto cell of the invention, and the home eNBcorresponds to a femto cell base station of the invention. Further, thePCI corresponds to a physical cell ID of the invention, and the CGIcorresponds to a unique cell ID of the invention.

Next, a configuration of the terminal apparatus 1 according to theembodiment will be described with reference to the block diagram inFIG. 1. As shown in FIG. 1, the terminal apparatus 1 (UE) comprises areception unit 10, a PCI acquisition unit 11, a whitelist storage unit12, a determination unit 13, a measurement unit 14, a measurement reportcreating unit 15, and a transmission unit 16.

The reception unit 10 receives a pilot channel for reception qualitymeasurement at a CSG cell as well as a synchronization channel for PCIacquisition from a home eNB, and receives a handover command (HOcommand) from the macro eNB.

The PCI acquisition unit 11 acquires a PCI from the synchronizationchannel information input from the reception unit 10, and outputs theacquired PCI to the determination unit 13 and the measurement reportcreating unit 15. The whitelist storage unit 12 stores a list of PCIsand CGIs of CSG cells that the terminal apparatus 1 is permitted toaccess. The information of the whitelist is output to the determinationunit 13.

The determination unit 13 determines a CGI of a CSG cell accessible tothe terminal apparatus 1 based on the PCI input from the PCI acquisitionunit 11 and the information input from the whitelist storage unit 12,and outputs the CGI to the measurement report creating unit 15. Themeasurement unit 14 measures reception quality based on the pilotchannel input from the reception unit 10, and outputs the result to themeasurement report creating unit 15.

The measurement report creating unit 15 creates a measurement reportbased on the PCI input from the PCI acquisition unit 11, the CGI of theCSG cell input from the determination unit 13 (the CGI of the CSG cellthat the terminal apparatus 1 desires to enter), and the receptionquality input from the measurement unit 14. The created measurementreport is output to the transmission unit 16. The transmission unit 16transmits the measurement report input from the measurement reportcreating unit 15 to the macro eNB through an antenna.

Next, a configuration of the base station apparatus 2 according to theembodiment will be described with reference to the block diagram in FIG.3. As shown in FIG. 3, the base station apparatus 2 (macro eNB)comprises a transmission unit 20, a reception unit 21, a CSG cell liststorage unit 22, a determination unit 23, and an HO request creatingunit 24.

The transmission unit 20 transmits an HO request input from the HOrequest creating unit 24 to the terminal apparatus 1. The reception unit21 receives a measurement report from the terminal apparatus 1. Thereception unit 21 also receives a list of CSG cells contained in themacro cell from the MME/GW. The CSG cell list storage unit 22 stores theCSG cell list input from the reception unit 21, which has been sent fromthe MME/GW. The CSG cell list information is input to the determinationunit 23.

The determination unit 23 compares the measurement report output fromthe reception unit 21, which has been sent from the terminal apparatus1, with the CSG cell list output from the CSG cell list storage unit 22to extract a CSG cell corresponding to the PCI included in themeasurement report from the terminal apparatus 1, and outputs aninstruction to create an HO request for the corresponding CSG cell tothe HO request creating unit 24. The HO request creating unit 24 createsthe HO request in response to the instruction from the determinationunit 23 and outputs the HO request to the transmission unit 20.

The operation of a thus configured wireless communication system will bedescribed with reference to FIGS. 4 to 6.

First, as a characteristic operation of the invention, description willbe made to the operation (i.e., signaling) of the entire system in thecase of the cell arrangement as shown in FIG. 2 when the terminalapparatus 1 that is camping on the macro cell is to handover to one oftwo CSG cells having the same PCI (i.e., the CSG cell [PCI #2, CGI #3]of HeNB 1).

FIG. 4 is a sequence diagram showing the operation of the wirelesscommunication system according to the embodiment. As shown in FIG. 4,the terminal apparatus 1 takes reception quality measurements of thehome eNB 1 (S1), and acquires the PCI (here, PCI #2). The terminalapparatus 1 adds the PCI of the home eNB 1 subjected to the measurementand the CGI (here, CGI #3) of an accessible CSG cell corresponding tothe PCI (the CSG cell that the terminal apparatus 1 desires to enter) tothe measurement result, and notifies the base station apparatus 2 (macroeNB) of a resultant measurement report MR (PCI #2, if CGI #3) (S2).

The base station apparatus 2 (macro eNB) determines a home eNB that hasthe “PCI” and “if CGI” notified from the terminal apparatus 1 (here, thehome eNB 1), and transmits an HO request to the home eNB 1 through aMobility Management Entity (MME)/Gateway (GW) (S3). If the handover ofthe terminal apparatus 1 is to be permitted, the home eNB 1 that hasreceived the HO request reserves in advance wireless resourcesappropriate for services provided to the terminal apparatus 1, performsacceptance control, and transmits an ACK to the HO request via theMME/GW to the base station apparatus 2 (macro eNB) (S4).

Upon receiving the ACK to the HO request from the home eNB 1, the basestation apparatus 2 (macro eNB) transmits an HO command for instructingthe terminal apparatus 1 to transfer to the CSG cell 1 (S5), and theterminal apparatus 1 transmits a random access preamble to the specifiedhome eNB (S6). After the home eNB transmits a random access response(S7) and synchronization is established, the terminal apparatus 1transmits an HO confirmation to the home eNB 1 (S8).

Next, the operation of components of the wireless communication system(the terminal apparatus 1 and the base station apparatus 2) will bedescribed.

FIG. 5 is a flow chart showing the operation of the terminal apparatus 1according to the embodiment. As shown in FIG. 5, the terminal apparatus1 receives a pilot channel and a synchronization channel from the homeeNB (S10), and takes reception quality measurements of the pilot channelof the home eNB (S11). The terminal apparatus 1 then determines whetheror not the CSG cell of handover destination is accessible (i.e., whetheror not it is the CSG cell that the terminal apparatus 1 desires toenter) based on the PCI acquired from the synchronization channel andthe whitelist. In cases where a CSG cell that has the PCI of a home eNBincluded in the whitelist is the best cell that has the best receptionquality (S12) for example, this determination is made by extracting theCGI of the CSG cell corresponding to the PCI from the whitelist (S13).The terminal apparatus 1 then creates a measurement report to which theCGI (if CGI) of the accessible CSG cell is added (S14), and transmitsthe measurement report to the base station apparatus 2 (macro eNB)(S15). Thereafter, once the terminal apparatus 1 receives an HO commandfrom the base station apparatus 2 (macro eNB) (S16), a handover to thehome eNB is performed (S17).

FIG. 6 is a flow chart showing the operation of the base stationapparatus 2 according to the embodiment. As shown in FIG. 6, uponreceiving the measurement report of the reception quality measurement atthe home eNB from the terminal apparatus 1 (S20), the base stationapparatus 2 (macro eNB) creates an HO request for the home eNB ofhandover destination based on the “PCI” and “if CGI” added to themeasurement report (S21) and transmits the HO request to the home eNBvia the MME/GW (S22). Upon receiving a response (HO request ACK) to theHO request from the home eNB via the MME/GW (S23), the base stationapparatus 2 (macro eNB) transmits an HO command for causing a transferto the home eNB to the terminal apparatus 1 based on the HO request ACK(S24).

According to the wireless communication system according to the firstembodiment, since the base station apparatus 2 (macro eNB) retrieves ahome eNB whose CGI (if CGI) is desired by the terminal apparatus 1 froma list to transmit an HO request, it is possible to reduce wastefulsignaling to two or more home eNBs that have the same PCI and reduceunnecessary resources being reserved in the borne eNBs.

In other words, to cope with the problem of a prior art that the basestation apparatus 2 (macro eNB) redundantly transmits HO requests evento other home eNBs that have the same PCI, the terminal apparatus 1 addsa CGI of a home eNB to which the terminal apparatus 1 desires tohandover to a measurement report and transmits the report to the basestation apparatus 2 (macro eNB) in the embodiment, so that the HOrequest is sent to only an appropriate home eNB.

Second Embodiment

A wireless communication system according to a second embodiment of thepresent invention will now be described below with reference to FIGS. 7to 10. In this unit, description will primarily be made to differencesfrom the first embodiment. Therefore, the configuration and operation ofthe second embodiment are similar to those of the first embodimentunless otherwise noted.

In this embodiment, it is assumed that a network policy of the basestation apparatus 2 (macro eNB) does not support a reliable handover andis of aggressive one that performs a handover regardless of the presenceor absence of an access permission. In other words, the embodiment isintended for a so-called aggressive base station apparatus 2 (macro eNB)of Release 8. The network policy of the base station apparatus 2 (macroeNB) is included in system information of the base station apparatus 2(macro eNB), and conveyed to the entire macro cell through a BroadcastControl Channel, or BCCH. Alternatively, the network policy of the basestation apparatus 2 (macro eNB) is included in a measurement controlmessage, and conveyed to the terminal apparatus 1 individually through aDedicated Control Channel.

FIG. 7 is a block diagram showing a configuration of a terminalapparatus 1 according to the embodiment. In the terminal apparatus 1according to the embodiment, a network policy identifying unit 17 and alocation information storage unit 18 are added to the configurationaccording to the first embodiment.

Similarly to the first embodiment, the reception unit 10 receives apilot channel as well as a synchronization channel from a home eNB, andreceives an HO command from the base station apparatus 2 (macro eNB).The reception unit 10 also receives system information including anetwork policy from the base station apparatus 2 (macro eNB). Thereception unit 10 has a GPS function that enables the reception unit 10to receive the current location information of the terminal.

The network policy identifying unit 17 identifies the network policy (ofaggressive one of Release 8) from the system information input from thereception unit 10, and outputs the result to the determination unit 13.The PCI acquisition unit 11, similarly to the first embodiment, acquiresa PCI from the synchronization channel information, and outputs theacquired PCI to the determination unit 13, the measurement reportcreating unit 15, and the location information storage unit 18.

The location information storage unit 18 stores the location information(for example, the latitude and longitude information) of the terminalinput from the reception unit 10, the PCI input from the PCI acquisitionunit 11, and the like in association with each other as fingerprintinformation of a CSG cell that the terminal apparatus 1 has previouslyaccessed. The information (fingerprint information) is output to thedetermination unit 13.

If it is determined that the base station apparatus 2 (macro eNB) is anaggressive macro eNB of Release 8 based on information output from thenetwork policy identifying unit 17, the determination unit 13 determineswhether the measured home eNB is that of an accessible CSG cell (i.e., aCSG cell that the terminal can access) based on the PCI input from thePCI acquisition unit 11 and the fingerprint information input from thelocation information storage unit 18.

For example, the determination unit 13 calculates the distance from theterminal apparatus 1 to the home eNB based on the PCI of the measuredhome eNB, the current location information of the terminal apparatus 1,and the fingerprint information (PCIs and the location information ofCSG cells that the terminal apparatus 1 has previously accessed), and ifthe distance is at or less than a predetermined reference distance (forexample, several tens to several hundreds meters), it is determined thatthe CSG cell is likely to be the one accessible to the terminalapparatus 1. On the other hand, if the distance is larger than thepredetermined reference distance, the determination is that it is likelythat the CSG cell is not the one accessible to the terminal apparatus 1.

As a result of the determination, if the measured home eNB is likely tobe an accessible CSG cell (i.e., a CSG cell that the terminal apparatus1 desires to enter), the determination unit 13 determines the CGI of theCSG cell accessible to the terminal apparatus 1, and outputs the CGI tothe measurement report creating unit 15. On the other hand, if it islikely that the measured home eNB is not an accessible CSG cell (i.e.,the CSG cell is not the one that the terminal apparatus 1 desires toenter) as a result of the determination, the determination unit 13outputs, to the measurement report creating unit 15, an instruction tocreate a measurement report to which a flag (non CSG flag) is addedindicating that the CSG cell is the one that the terminal apparatus 1does not desire to enter. Alternatively, the determination unit 13outputs an instruction to measure another frequency (for example, f2) ofthe macro cell (inter-frequency measurement) to the measurement unit 14.

Similarly to the first embodiment, the measurement unit 14 measuresreception quality based on the pilot channel input from the receptionunit 10, and outputs the result to the measurement report creating unit15. The measurement unit 14 starts to measure another frequency (forexample, f2) of the macro cell based on the inter-frequency measurementinstruction input from the determination unit 13.

FIG. 8 is a block diagram showing a configuration of a base stationapparatus 2 according to the embodiment. In the base station apparatus 2according to the embodiment, a network policy storage unit 25, a systeminformation creating unit 26, and a measurement control informationcreating unit 27 are added to the configuration according to the firstembodiment.

The network policy storage unit 25 stores the network policy (ofaggressive one of Release 8) information of the base station apparatus 2(macro eNB). The network policy information is input to the systeminformation creating unit 26. The system information creating unit 26creates system information including information output from the networkpolicy storage unit 25. The created system information is input to thetransmission unit 20.

Similarly to the first embodiment, the determination unit 23 comparesthe measurement report from the terminal apparatus 1 with the CSG celllist to extract a CSG cell corresponding to the PCI included in themeasurement report from the terminal apparatus 1, and outputs aninstruction to create an HO request for the corresponding CSG cell tothe HO request creating unit 24. If the “non CSG flag” is included inthe measurement report from the terminal apparatus 1, the determinationunit 23 also inputs, to the measurement control information creatingunit 27, an instruction to create a measurement control including aninstruction to measure another frequency (for example, f2) of the macrocell (inter-frequency measurement).

The measurement control information creating unit 27 creates themeasurement control including an instruction to measure anotherfrequency (for example, f2) of the macro cell in response to theinstruction from the determination unit 23. The created measurementcontrol message is input to the transmission unit 20. The transmissionunit 20 transmits the system information input from the systeminformation creating unit 26, the HO request input from the HO requestcreating unit 24, the measurement control message input from themeasurement control information creating unit 27, and the like to theterminal apparatus 1.

The operation of a thus configured wireless communication system will bedescribed with reference to FIGS. 9 to 11.

FIGS. 9 and 10 are sequence diagrams showing the operation of the entirewireless communication system according to the embodiment. First, withreference to FIG. 9, description will be made to the operation in caseswhere it is determined that the measured home eNB is likely to be a homeeNB accessible to the terminal apparatus 1 from the PCI and fingerprintinformation acquired by the terminal apparatus 1.

As shown in FIG. 9, the terminal apparatus 1 receives the systeminformation (BCCH) from the base station apparatus 2 (macro eNB) andidentifies the network policy of the base station apparatus 2 (macroeNB) (S30). In this case, the network policy of the base stationapparatus 2 (macro eNB) is identified as an aggressive eNB of Release 8.

The terminal apparatus 1 takes reception quality measurements of thehome eNB (home eNB 1) (S31), and acquires the PCI (here, PCI #2). Theterminal apparatus 1 retains PCIs and the location information(fingerprint information) of CSG cells that the terminal apparatus 1 haspreviously camped on, and in this case, it is determined that themeasured home eNB (home eNB 1) is likely to be a home eNB accessible tothe terminal apparatus 1 from the PCI and fingerprint informationacquired by the terminal apparatus 1.

The terminal apparatus 1 then adds the PCI of the home eNB (home eNB 1)subjected to the reception quality measurement and the CGI (here, CGI#3) of an accessible CSG cell corresponding to the PCI (the CSG cellthat the terminal apparatus 1 desires to enter) to the reception qualitymeasurement result, and notifies the base station apparatus 2 (macroeNB) of a resultant measurement report MR (PCI #2, if CGI #3) (S32).

The base station apparatus 2 (macro eNB) determines a home eNB that hasthe “PCI” and “if CGI” notified from the terminal apparatus 1 (here, thehome eNB 1), and transmits an HO request to the home eNB 1 through theMME/GW (S33). If the handover of the terminal apparatus 1 is to bepermitted, the home eNB 1 that has received the HO request reserves inadvance wireless resources appropriate for services provided to theterminal apparatus 1, performs acceptance control, and transmits an ACKto the HO request via the MME/GW to the base station apparatus 2 (macroeNB) (S34).

Upon receiving the ACK to the HO request from the home eNB 1, the basestation apparatus 2 (macro eNB) transmits an HO command for instructingthe terminal apparatus 1 to transfer to the CSG cell 1 (S35), and theterminal apparatus 1 transmits a random access preamble to the specifiedhome eNB (S36). After the home eNB transmits a random access response(S37) and synchronization is established, the terminal apparatus 1transmits an HO confirmation to the borne eNB 1 (S38).

Next, with reference to FIG. 10, description will be made to theoperation in cases where the determination is that it is likely that themeasured home eNB is not a home eNB accessible to the terminal apparatus1 from the PCI and fingerprint information acquired by the terminalapparatus 1.

As shown in FIG. 10, the terminal apparatus 1 receives the systeminformation (BCCH) from the base station apparatus 2 (macro eNB) andidentifies the network policy of the base station apparatus 2 (macroeNB) (S40). In this case, the base station apparatus 2 (macro eNB) isalso identified as an aggressive eNB of Release 8.

The terminal apparatus 1 takes reception quality measurements of thehome eNB (home eNB 1) (S41), and acquires the PCI (here, PCI #2). Theterminal apparatus 1 retains PCIs and the location information(fingerprint information) of CSG cells that the terminal apparatus 1 haspreviously camped on, and in this case, the determination is that it islikely that the measured home eNB (home eNB 2) is not a home eNBaccessible to the terminal apparatus 1 from the PCI and fingerprintinformation acquired by the terminal apparatus 1.

For example, if the terminal apparatus 1 does not have a high level ofself-decision function (for example, the terminal apparatus 1 is aRelease 8 terminal), the terminal apparatus 1 adds the PCI of the homeeNB (home eNB 2) subjected to the reception quality measurement and aflag “non CSG flag” for notifying that the CSG cell corresponding to thePCI is not an accessible CSG cell (i.e., the CSG cell is not the onethat the terminal apparatus 1 desires to enter) to the reception qualitymeasurement result, and notifies the base station apparatus 2 (macroeNB) of a resultant measurement report MR (PCI #2, non CSG flag) (S42).

Upon receiving the measurement report to which the “non CSG flag” isadded, the base station apparatus 2 (macro eNB) transmits a measurementcontrol message for instructing the terminal apparatus 1 to measureanother frequency (for example, f2) of the macro cell (inter-frequencymeasurement) (S43). Upon receiving the measurement control message fromthe base station apparatus 2 (macro eNB), the terminal apparatus 1starts to measure another frequency (for example, f2) of the macro cell(S44), and transmits a measurement report to the base station apparatus2 (macro eNB) (S45).

If the terminal apparatus 1 has a high level of self-decision function(the terminal apparatus 1 is a Release 9 terminal), the terminalapparatus 1 automatically starts to measure another frequency (forexample, f2) of the macro cell (inter-frequency measurement) (S44) atthe time when the terminal apparatus 1 estimates that the measured CSGcell is not an accessible CSG cell, and transmits a measurement reportto the base station apparatus 2 (macro eNB) (S45).

FIG. 11 is a flow chart showing the operation of the terminal apparatus1 according to the embodiment. As shown in FIG. 11, the terminalapparatus 1 first receives a network policy included in systeminformation from the base station apparatus 2 (macro eNB) (S50). Next,the terminal apparatus 1 takes reception quality measurements of a pilotchannel of a home eNB (S51), and if a CSG cell that has the PCI of ahome eNB contained in the whitelist is the best cell of the bestreception quality (S52), determination is made on the network policy.

If it is determined that the base station apparatus 2 (macro eNB) is anaggressive macro eNB of Release 8 (S53) as a result of the determinationon the network policy, the terminal apparatus 1 uses the acquired PCIand fingerprint information to determine whether the home eNB isaccessible to the terminal apparatus 1 (S54). If it is determined thatthe CSG cell is likely to be the one accessible to the terminalapparatus 1, the terminal apparatus 1 creates a measurement reportincluding the CGI (if CGI) of the accessible CSG cell, and transmits themeasurement report to the base station apparatus 2 (macro eNB) (S55).

If the determination is that it is likely that the CSG cell is not theone accessible to the terminal apparatus 1 and if the terminal apparatus1 has a high level of self-decision function (for example, the terminalapparatus 1 is a Release 9 terminal) (S56), the terminal apparatus 1starts to take reception quality measurements of another frequency ofthe base station apparatus 2 (macro eNB) (inter-frequency measurement)without transmitting a measurement report (S57).

On the other hand, if the terminal apparatus 1 does not have a highlevel of self-decision function (for example, the terminal apparatus 1is a Release 8 terminal), the terminal apparatus 1 creates a measurementreport including a flag for notifying that the CSG cell is not anaccessible CSG cell, and transmits the measurement report to the basestation apparatus 2 (macro eNB) (S58).

According to the wireless communication system according to the secondembodiment, similar effects to the first embodiment can be achieved.

The embodiment is intended for an aggressive base station apparatus 2(macro eNB) of Release 8. In this case, when the terminal sends a CGI(if CGI) of an accessible CSG cell with a measurement report, it isconceivable that a handover instruction may be provided regardless ofwhether the CSG cell is actually the one accessible to the terminalapparatus 1. In other words, in the case of an aggressive macro eNB ofRelease 8, it is conceivable that the terminal apparatus 1 starts HOprocedures for home eNBs that are not listed in the whitelist, causing aproblem of wasteful signaling. Also similarly to the first embodiment,sending only a PCI in a measurement report may cause a problem of HOrequests being sent to more than one home eNB.

In this embodiment, therefore, in view of the fact that the base stationapparatus 2 (macro eNB) acts in a different way according to the networkpolicy when a measurement report is received, it is possible to suppresswasteful signaling and an increase of message size of a measurementreport by determining information to be sent in the measurement reportdepending on the network policy of the base station apparatus 2 (macroeNB).

In particular, according to the wireless communication system accordingto the embodiment, if the base station apparatus 2 (macro eNB) is anaggressive macro eNB of Release 8, the terminal apparatus 1 useslocation information by means of fingerprints to confirm confidencebefore the terminal apparatus 1 sends “if CGI” in a measurement report.It is therefore possible to reduce wasteful signaling such as handoverinstructions provided to CSG cells that are not listed in the whitelist.In this way, signaling overhead can be reduced by considering actionstaken by the base station apparatus 2 (macro eNB) at the time when areception quality measurement result is received from the terminalapparatus 1 and transmitting a suitable reception quality measurementresult depending on the network policy of the base station apparatus 2(macro eNB).

Third Embodiment

A wireless communication system according to a third embodiment of thepresent invention will now be described below with reference to FIGS. 12to 15. In this unit, description will primarily be made to differencesfrom the second embodiment. Therefore, the configuration and operationof the third embodiment are similar to those of the second embodimentunless otherwise noted.

In this embodiment, it is assumed that a network policy of the basestation apparatus 2 (macro eNB) does not support a reliable handover andis of non-aggressive that does not perform a handover regardless of thepresence or absence of an access permission. In other words, theembodiment is intended for a so-called non-aggressive macro eNB ofRelease 8.

FIG. 12 is a block diagram showing a configuration of a terminalapparatus 1 according to the embodiment. The terminal apparatus 1according to the embodiment is not provided with a location informationstorage unit 18. Further in this embodiment, if it is determined thatthe base station apparatus 2 (macro eNB) is a non-aggressive macro eNBof Release 8 based on information output from the network policyidentifying unit 17, the determination unit 13 outputs, to themeasurement report creating unit 15, an instruction to create ameasurement report to which a CGI of a measured CSG cell is not added(i.e., a measurement report including a PCI and a reception qualitymeasurement result of the measured CSG cell). Incidentally, the processis performed in cases where the terminal apparatus 1 does not have ahigh level of self-decision function (for example, the terminalapparatus 1 is a Release 8 terminal). If the terminal apparatus 1 has ahigh level of self-decision function (for example, the terminalapparatus 1 is a Release 9 terminal), the determination unit 13 outputsan instruction to measure another frequency (for example, f2) of themacro cell (inter-frequency measurement) to the measurement unit 14.

FIG. 13 is a block diagram showing a configuration of a base stationapparatus 2 according to the embodiment. The base station apparatus 2,according to the embodiment, is not provided with a CSG cell liststorage unit 22. Further in this embodiment, the network policy storageunit 25 stores a network policy (of non-aggressive of Release 8)information of the base station apparatus 2 (macro eNB). When it isdetermined that the measured cell is not a macro cell (it is a CSG cell)from a PCI included in a measurement report from the terminal apparatus1, the determination unit 23 inputs, to the measurement controlinformation creating unit 27, an instruction to create a measurementcontrol message including an instruction to measure another frequency(for example, f2) of the macro cell (inter-frequency measurement).

The operation of a thus configured wireless communication system will bedescribed with reference to FIGS. 14 and 15.

FIG. 14 is a sequence diagram showing the operation of the entirewireless communication system according to the embodiment. As shown inFIG. 14, the terminal apparatus 1 receives system information (BCCH)from the base station apparatus 2 (macro eNB) and identifies a networkpolicy of the base station apparatus 2 (macro eNB) (S60). In this case,the network policy of the base station apparatus 2 (macro eNB) isidentified as a non-aggressive eNB of Release 8.

The terminal apparatus 1 takes reception quality measurements of thehome eNB (home eNB 1) (S61), and acquires the PCI (here, PCI #2). Atthis time, it is possible to determine that the measured cell is a CSGcell from the acquired PCI and a whitelist retained by the terminalapparatus 1. It is also possible to determine that the base stationapparatus 2 (macro eNB) does not retain a list of CSG cells from thenetwork policy of the base station apparatus 2 (macro eNB).

For example, if the terminal apparatus 1 does not have a high level ofself-decision function (for example, the terminal apparatus 1 is aRelease 8 terminal), the terminal apparatus 1 notifies the base stationapparatus 2 (macro eNB) of only a reception quality measurement resultto which the PCI of the home eNB 1 subjected to the reception qualitymeasurement is added (S62). In other words, a CGI of the measured homeeNB 1 is not notified to the base station apparatus 2 (macro eNB). Uponreceiving a measurement report from the terminal apparatus 1, the basestation apparatus 2 (macro eNB) transmits a measurement control messagefor instructing the terminal apparatus 1 to measure another frequency(for example, f2) of the macro cell (inter-frequency measurement) (S63).Upon receiving the measurement control message from the base stationapparatus 2 (macro eNB), the terminal apparatus 1 starts to measureanother frequency (for example, f2) of the macro cell (S64), andtransmits a measurement report to the base station apparatus 2 (macroeNB) (S65).

If the terminal apparatus 1 has a high level of self-decision function(the terminal apparatus 1 is a Release 9 terminal), the terminalapparatus 1 automatically starts to measure another frequency (forexample, f2) of the macro cell (inter-frequency measurement) (S64) atthe time when it is determined that the measured cell is a CSG cell andthe base station apparatus 2 (macro eNB) is a non-aggressive macro eNBof Release 8, and transmits a measurement report to the base stationapparatus 2 (macro eNB) (S65).

FIG. 15 is a flow chart showing the operation of the terminal apparatus1 according to the embodiment. As shown in FIG. 15, the terminalapparatus 1 first receives a network policy included in systeminformation from the base station apparatus 2 (macro eNB) (S70). Next,the terminal apparatus 1 takes reception quality measurements of a pilotchannel of a home eNB (S71), and if a CSG cell that has the PCI of ahome eNB contained in the whitelist is the best cell of the bestreception quality (S72), determination on the network policy is made.

If it is determined that the base station apparatus 2 (macro eNB) is anon-aggressive macro eNB of Release 8 (S73) as a result of theexamination on the network policy, and if the terminal apparatus 1 has ahigh level of self-decision function (for example, the terminalapparatus 1 is a Release 9 terminal) (S74), the terminal apparatus 1starts to take reception quality measurements of another frequency ofthe base station apparatus 2 (macro eNB) (inter-frequency measurement)without transmitting a measurement report (S75).

On the other hand, if the terminal apparatus 1 does not have a highlevel of self-decision function (for example, the terminal apparatus 1is a Release 8 terminal), the terminal apparatus 1 creates a measurementreport to which only the PCI of the CSG cell is added (i.e., ameasurement report to which a CGI of the CSG cell is not added), andtransmits the measurement report to the base station apparatus 2 (macroeNB) (S76).

According to the wireless communication system according to the thirdembodiment, similar effects to the first embodiment can be achieved.

The embodiment is intended for a non-aggressive macro eNB of Release 8.In this case, the base station apparatus 2 (macro eNB) does notcompletely support a handover for CSG cells and it is conceivable thatthe base station apparatus 2 (macro eNB) does not retain a list of homeeNBs contained in the macro cell. In this case, even when the terminalapparatus 1 sends a CGI (if CGI) of an accessible CSG cell with ameasurement report, the base station apparatus 2 (macro eNB) cannot takean action because of the lack of the list of CSG cells, causing aproblem of an increase of message size of a measurement report due tounnecessary information.

In this embodiment, therefore, it is possible to minimize a message sizeby sending only a PCI of a home eNB acquired during measurement.

In particular, according to the wireless communication system accordingto the embodiment, if the base station apparatus 2 (macro eNB) is anon-aggressive macro eNB of Release 8, the terminal apparatus 1 sendsonly a PCI of a home eNB acquired during measurement, so that themessage size can be minimized.

Incidentally, the base station apparatus 2 (macro eNB) may retain a CSGcell list received from the MME/GW. In this case, if two or more CSGcells that have the same PCI are present in the CSG cell list, the basestation apparatus 2 (macro eNB) may perform similar operations. If thesame PCI (a certain PCI) is held by only one CSG cell in the CSG celllist, an HO request may be transmitted to the corresponding home eNB.

Fourth Embodiment

A wireless communication system according to a fourth embodiment of thepresent invention will now be described below with reference to FIGS. 16to 19. In this unit, description will primarily be made to differencesfrom the second embodiment. Therefore, the configuration and operationof the fourth embodiment are similar to those of the second embodimentunless otherwise noted.

In this embodiment, it is assumed that a network policy of the basestation apparatus 2 (macro eNB) supports a reliable handover. In otherwords, the embodiment is intended for a so-called Release 9 macro eNB.

FIG. 16 is a block diagram showing a configuration of a terminalapparatus 1 according to the embodiment. The terminal apparatus 1according to the embodiment is not provided with a location informationstorage unit 18 and a DRX control unit 19 is added. Discontinuousreception (DRX) is a control method of the terminal apparatus 1 toreceive data intermittently when the receiving data is discontinuous inorder to suppress receiving power consumption. The DRX includes long DRXand short DRX, whose period of time during which data is not received isdifferent from each other. The long DRX is used in cases where data isnot received for a long period, since the longer the period during whichdata is not received is, the more the power consumption of the terminalapparatus 1 is suppressed. The terminal apparatus 1 is instructed toimplement the DRX and to use either of the long DRX or the short DRXwhen the terminal apparatus 1 establishes a connection with the basestation apparatus 2. The terminal apparatus 1 does not implement the DRXwithout an instruction from the base station apparatus 2. Further inthis embodiment, if it is determined that the base station apparatus 2(macro eNB) is a macro eNB of Release 9 based on information output fromthe network policy identifying unit 17, the determination unit 13inputs, to the measurement unit 14, an instruction to receive BCCH of aCSG cell to acquire a CGI while the terminal implements the long DRX. Onthe other hand, if the terminal does not implement the long DRX, thedetermination unit 13 outputs, to the measurement report creating unit15, an instruction to create a measurement report including a PCI and areception quality measurement result of the measured CSG cell. Based onan instruction in a measurement control message output from thereception unit 10, the determination unit 13 inputs an instruction toimplement the long DRX to the DRX control unit 19 or outputs aninstruction to measure another frequency (for example, f2) of the macrocell (inter-frequency measurement) to the measurement unit 14. The DRXcontrol unit 19 starts to implement the long DRX according to the outputfrom the determination unit 13.

FIG. 17 is a block diagram showing a configuration of a base stationapparatus 2 according to the embodiment. A DRX changing instruction unit28 is added to the base station apparatus 2 according to the embodiment.Further in this embodiment, the network policy storage unit 25 stores anetwork policy (Release 9) information of the base station apparatus 2(macro eNB). If a PCI and a CGI are added to a measurement report outputfrom the reception unit 21, which has been sent from the terminalapparatus 1, the determination unit 23 compares it with a CSG cell listoutput from the CSG cell list storage unit 22 to extract a CSG cellcorresponding to a combination of the PCI and the CGI included in themeasurement report from the terminal apparatus 1, and outputs aninstruction to create an HO request for the corresponding CSG cell tothe HO request creating unit 24. If a CGI is not added to a measurementreport from the terminal apparatus 1, the determination unit 23 inputs,to the DRX changing instruction unit 28, an instruction for the terminalapparatus 1 to implement the long DRX, or inputs, to the measurementcontrol information creating unit 27, an instruction to create ameasurement control message including an instruction to measure anotherfrequency (for example, f2) of the macro cell (inter-frequencymeasurement).

In response to the instruction from the determination unit 23, the DRXchanging instruction unit 28 inputs, to the measurement controlinformation creating unit 27, an instruction to create a measurementcontrol message including an instruction to implement the long DRX. Inresponse to the instruction from the determination unit 23, themeasurement control information creating unit 27 creates a measurementcontrol message including an instruction to measure another frequency(for example, f2) of the macro cell, and inputs it to the transmissionunit 20. In response to the instruction from both the determination unit23 and the DRX changing instruction unit 28, the measurement controlinformation creating unit 27 creates a measurement control messageincluding an instruction to implement the long DRX, and inputs it to thetransmission unit 20.

The operation of a thus configured wireless communication system will bedescribed with reference to FIGS. 18 and 19.

FIG. 18 is a sequence diagram showing the operation of the entirewireless communication system according to the embodiment. As shown inFIG. 18, the terminal apparatus 1 receives the system information (BCCH)from the base station apparatus 2 (macro eNB) and identifies the networkpolicy of the base station apparatus 2 (macro eNB) (S80). In this case,the network policy of the base station apparatus 2 (macro eNB) isidentified as an eNB of Release 9.

The terminal apparatus 1 takes reception quality measurements of thehome eNB (home eNB 1) (S81), and acquires the PCI (here, PCI #2).Determination is then made to whether the terminal apparatus 1implements the long discontinuous reception (DRX) (S82).

If it is determined that the terminal apparatus 1 does not implement thelong DRX, the terminal apparatus 1 adds only a PCI of the measured CSGcell to a reception quality measurement result, and transmits themeasurement report (PCI #2) to the base station apparatus 2 (macro eNB).Upon receiving the measurement report from the terminal apparatus 1, thebase station apparatus 2 (macro eNB) transmits a measurement controlmessage for instructing the terminal apparatus 1 to implement the longDRX and acquire a CGI (i.e., to receive BCCH) of the CSG cell (S84).Instead, the base station apparatus 2 (macro eNB) may transmit ameasurement control message with an instruction to measure anotherfrequency (for example, f2) of the macro cell (inter-frequencymeasurement).

If it is determined that the terminal apparatus 1 implements the longDRX, and when it is determined that the measured cell is a CSG cell fromthe acquired PCI and a whitelist, the terminal apparatus 1 automaticallyreceives BCCH of the CSG cell to acquire a CGI (S85). The terminalapparatus 1 then creates a measurement report MR (PCI #2, CGI #3) towhich the PCI and the CGI are added, and transmits it to the basestation apparatus 2 (macro eNB) (S86).

Upon receiving a measurement report from the terminal apparatus 1, thebase station apparatus 2 (macro eNB) determines the corresponding CSGcell from the PCI and the CGI added to the measurement report and a listof CSG cells retained by the base station apparatus 2, and transmits anHO request to a home eNB (home eNB 1) of the corresponding CSG cell(S87). If the handover of the terminal apparatus 1 is to be permitted,the home eNB 1 that has received the HO request reserves in advancewireless resources appropriate for services provided to the terminalapparatus 1, performs acceptance control, and transmits an ACK to the HOrequest via the MME/GW to the base station apparatus 2 (macro eNB)(S88).

Upon receiving the ACK to the HO request from the home eNB 1, the basestation apparatus 2 (macro eNB) transmits an HO command for instructingthe terminal apparatus 1 to transfer to the CSG cell 1 (S89), and theterminal apparatus 1 transmits a random access preamble to the specifiedhome eNB (S810). After the home eNB transmits a random access response(S811) and synchronization is established, the terminal apparatus 1transmits an HO confirmation to the home eNB 1 (S812).

FIG. 19 is a flow chart showing the operation of the terminal apparatus1 according to the embodiment. As shown in FIG. 19, the terminalapparatus 1 first receives a network policy included in systeminformation from the base station apparatus 2 (macro eNB) (S90). Next,the terminal apparatus 1 takes reception quality measurements of a pilotchannel of a home eNB (S91), and if a CSG cell that has the PCI of ahome eNB contained in the whitelist is the best cell of the bestreception quality (S92), examination is made on the network policy.

If it is determined that the base station apparatus 2 (macro eNB) is amacro eNB of Release 9 (S93) as a result of the examination on thenetwork policy, determination is made on whether or not the terminalapparatus 1 implements the long DRX (S94). If the terminal apparatus 1implements the long DRX, the terminal apparatus 1 receives BCCH of theCSG cell to acquire a CGI (S95). The terminal apparatus 1 then creates ameasurement report including the acquired PCI and CGI and a receptionquality measurement result, and transmits the measurement report to thebase station apparatus 2 (macro eNB) (S96). On the other hand, if theterminal apparatus 1 does not implement the long DRX, the terminalapparatus 1 creates a measurement report including the PCI and areception quality measurement result, and transmits it to the basestation apparatus 2 (macro eNB) (S97).

According to the wireless communication system according to the fourthembodiment, similar effects to the first embodiment can be achieved.

The embodiment is intended for a macro eNB of Release 9. In this case,since the base station apparatus 2 (macro eNB) supports a reliablehandover to a CSG cell, it is conceivable that the base stationapparatus 2 (macro eNB) provides a handover instruction after the basestation apparatus 2 confirms that the CSG cell is accessible to theterminal apparatus 1. Therefore, upon receiving a measurement report ofa home eNB from the terminal apparatus 1, it is conceivable that thebase station apparatus 2 immediately instructs the terminal apparatus 1to read a CGI of the home eNB. In this case, a CGI (if CGI) of theaccessible CSG cell sent by the terminal in the first measurement reportis redundant and may cause a problem of an increase of message size of ameasurement report.

In this embodiment, therefore, it is possible to minimize the messagesize of the measurement report by sending only a PCI of a home eNBacquired during measurement in the first measurement report.

In particular, according to the wireless communication system accordingto the embodiment, considering the fact that in cases where the basestation apparatus 2 (macro eNB) is a macro eNB of Release 9, the basestation apparatus 2 immediately instructs the terminal apparatus 1 toread a CGI of a home eNB upon receiving a measurement report of the homeeNB from the terminal apparatus 1, the terminal apparatus 1 sends only aPCI of the home eNB acquired during measurement in the first measurementreport. It is therefore possible to minimize the message size of themeasurement report.

Embodiments according to the present invention have been described byway of illustration. The scope of the invention, however, is not limitedthereto and alteration and modification can be made thereto withoutdeparting from the scope of the invention as defined by the appendedclaims.

For example, description has been made above to the cases where the basestation apparatus 2 (macro eNB) transmits a network policy throughoutthe system by means of system information. The scope of the invention,however, is not limited thereto and the base station apparatus 2 (macroeNB) may transmit a network policy to the terminal apparatus 1individually by means of a measurement control message.

Although currently possible preferred embodiments of the invention havebeen described above, it is understood that various modifications can bemade to the embodiments and it is intended that all such modificationsthat fall within the true spirit and scope of the invention are coveredby the attached claims.

INDUSTRIAL APPLICABILITY

As described above, the radio transmitting/receiving apparatus accordingto the present invention can effectively suppress wasteful signaling andprevent unnecessary resources from being reserved, and is useful for atechnique for performing a handover from a macro cell to a CSG cell, andthe like.

REFERENCE SIGNS LIST

-   1 terminal apparatus (UE)-   2 base station apparatus (macro eNB)-   10 reception unit-   11 PCI acquisition unit-   12 whitelist storage unit-   13 determination unit-   14 measurement unit-   15 measurement report creating unit-   16 transmission unit-   17 network policy identifying unit-   18 location information storage unit-   19 DRX control unit-   20 transmission unit-   21 reception unit-   22 CSG cell list storage unit-   23 determination unit-   24 HO request creating unit-   25 network policy storage unit-   26 system information creating unit-   27 measurement control information creating unit-   28 DRX changing instruction unit

1. A wireless communication apparatus comprising: a reception unit that receives, from a femto cell base station, a pilot channel signal for reception quality measurement and a synchronization channel signal for synchronization, wherein the femto cell is included in a macro cell; a storage unit that stores a list indicating accessible femto cells and physical cell IDs of the accessible femto cells; a determination unit that determines whether the femto cell is positionally accessible or not based on the physical cell IDs in the list and the physical cell ID of the femto cell acquired from the received synchronization channel signal; a measurement report creation unit that creates a report for notifying the macrocell base station, the report including information that is a determination result of the determination unit and that is related to whether the femto cell is positionally accessible or not, and a transmission unit that transmits the created report to the macrocell base station.
 2. The wireless communication apparatus according to claim 1, wherein the storage unit further stores location information of a previously accessed femto cell base station with the corresponding physical cell ID of the femto cell base station.
 3. The wireless communication apparatus according to claim 2, wherein the determination unit calculates a distance from the wireless communication apparatus to the femto cell base station based on current location information of the wireless communication apparatus, the location information of the previously accessed femto cell base station, and the corresponding physical cell ID of the femto cell base station, wherein in case the calculated distance is equal to or less than a predetermined reference distance, the determination unit determines the femto cell is accessible to the wireless commination apparatus.
 4. The wireless communication apparatus according to claim 1, wherein the measurement report creation unit is configured to create a report including reception quality of the femto cells and the physical cell IDs of the femto cells.
 5. The wireless communication apparatus according to claim 1, wherein the reception unit is capable of receiving, from the macro cell base station, system information including a network policy relating to a handover from a macro cell to a femto cell or a measurement control message including the network policy, the determination unit has a function for examining a network policy of the macro cell base station, and the measurement report creating unit creates the measurement report depending on the network policy of the macro cell base station.
 6. The wireless communication apparatus according to claim 1, wherein the measurement report creating unit adds to the measurement report, if it is determined that the femto cell of handover destination is not accessible, the physical cell ID of the femto cell determined to be inaccessible and a notification indicating that the femto cell is not accessible.
 7. The wireless communication apparatus according to claim 1, further comprising a measurement unit which takes reception quality measurements on another frequency band managed by the macro cell base station if it is determined that the femto cell of handover destination is not accessible.
 8. The wireless communication apparatus according to claim 5, wherein the measurement report creating unit does not add to the measurement report, if it is determined that a network policy of the macro cell base station does not support a reliable handover and is of non-aggressive type that does not perform a handover regardless of presence or absence of an access permission, the unique cell ID of the femto cell of handover destination determined to be accessible.
 9. The wireless communication apparatus according to claim 8, further comprising a measurement unit which takes reception quality measurements on another frequency band managed by the macro cell base station if it is determined that a network policy of the macro cell base station does not support a reliable handover and is of non-aggressive type that does not perform a handover regardless of presence or absence of an access permission.
 10. The wireless communication apparatus according to claim 5, wherein the determination unit determines, if it is determined that a network policy of the macro cell base station supports a reliable handover, whether or not long discontinuous reception with which time required to acquire the unique cell ID is reserved is implemented, and the measurement report creating unit does not add to the measurement report, if it is determined that the long discontinuous reception is not implemented, the unique cell ID of the femto cell of handover destination determined to be accessible.
 11. The wireless communication apparatus according to claim 10, wherein the measurement report creating unit adds to the measurement report, if it is determined that the long discontinuous reception is implemented, the physical cell ID and the unique cell ID of the femto cell determined to be accessible.
 12. A method performed by a wireless communication apparatus comprising: receiving, from a femto cell base station, a pilot channel signal for reception quality measurement and a synchronization channel signal for synchronization, wherein the femto cell is included in a macro cell; storing a list indicating accessible femto cells and physical cell IDs of the accessible femto cells; determining whether the femto cell is positionally accessible or not based on the physical cell IDs in the list and the physical cell ID of the femto cell acquired from the received synchronization channel signal; creating a report for notifying the macrocell base station, the report including information that is a determination result in the determining step and that is related to whether the femto cell is positionally accessible or not, and transmitting the created report to the macrocell base station. 